Scientific Forecaster Discussion

Synopsis... cold front tonight. Front stalls to the south with low pressure moving along the front Wednesday night. Snow showers linger on Thursday. High pressure Friday.

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Near term /through Wednesday/... models continue to advertise a heavy rain event over the next 24 hours...transitioning to a heavy snow event by Wednesday afternoon mainly west of the Ohio River. A slow moving cold front will drop southeast across the area later tonight and Wednesday and will be the focus for widespread rain that will be heavy at times. A Flood Watch remains in effect for the entire area from this evening Onward...although the heaviest rains tonight will be over the northwest half of the area...spreading southeast over the remainder of the area by Wednesday. Snowmelt will also be a factor especially in the mountains to enhance potential flooding. For the transition to snow...we will blend the faster GFS/CMC solution and the slower NAM/ECMWF. In any event...all models show a heavy rain to be followed by a heavy snow event. So the transition to snow will be occurring over mainly southeast Ohio Wednesday afternoon. We have upgraded the Winter Storm Watch to a warning for most of the counties along and west of the Ohio River Wednesday afternoon. The remainder opf the area...except for the far south...remains in a Winter Storm Watch. Temperatures will be mild tonight...not falling much until the cold front starts progressing across the area. The front itself will most likely reach the mountains by Wednesday morning...with falling temperatures through the 30s during Wednesday. So...the main rain event will be from one wave moving along the slowly progressive front tonight and Wednesday morning...then followed by a second wave in the colder that will be responsible for the change to snow.

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Short term /Wednesday night through Friday/... an extremely strong upper level jet will provide support for a prolonged period of rain and snow associated with a slow moving cold front. By Wednesday night the rain will be transitioning to sleet and eventually to snow. A Winter Storm Watch remains in effect for much of the area and winter storm warnings have been hoisted for the western portion of the forecast area where confidence is higher in receiving impactful winter weather. Kept the watch in effect for the eastern portion of the area due to the uncertainty associated with the timing of the changeover and the duration of sleet that should occur during the transition period.

Models generally agree on the intensity and duration with the GFS being the one outlier pushing the cold air through faster and subsequently keeping the area a bit drier. Opted to still consider this in the forecast...but blended towards the slower wetter solutions which is more in line with the wpc thinking.

Precipitation should start to subside by Thursday afternoon. High pressure builds in on Friday.

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Long term /Friday night through Tuesday/... high pressure in place to start the long term period...gradually being squashed to the south as an upper level shortwave trough drops through the western Great Lakes Sunday. Models struggling some with this feature...both in speed and just how far south precipitation with this will make it. Have another 500mb shortwave trough following the first around Monday. 00z European model (ecmwf) tries to keep these to features separate...while GFS does not have much of a break between them. Ended up with a near 50/50 blend of GFS/European model (ecmwf) through the long term for probability of precipitation. Generally stuck close to wpc for temps/winds.

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Aviation /21z Tuesday through Sunday/... have a break in the rain this afternoon. Look for general MVFR conditions to prevail across southeast Ohio and possibly just VFR conditions in the warm sector across ekn amid downslope winds. IFR conditions look to develop on east slopes including kbkw this afternoon. There will be only a slight chance of an embedded thunderstorm southeast portions of area this afternoon and night.

The front sags southeast tonight...clearing southeast Ohio by 06z...c WV by 09z...and into the mountains by 12z. Heavy rain will fall along the baroclinic zone...sending aviation conditions into IFR or worse.

Southerly winds will generally be light in The Lowlands...but gusts will be increasing to around 25 knots on Mountain Ridge tops this morning...including kbkw.

Forecast confidence and alternate scenarios through 18z Wednesday...

Forecast confidence: low to medium.

Alternate scenarios: lowering of flight categories to MVFR/IFR will vary with onset of the rain tonight.

Experimental table of flight category objectively shows consistency of weather forecast office forecast to available model information: h = high: taf consistent with all models or all but one model. M = medium: taf has varying level of consistency with models. L = low: taf inconsistent with all models or all but one model.